Broach checking machine



May 21, l1957 H. J. FLAIR 2,792,635

BROACH CHECKING MACHINE Filed March 9, 1956 3 Sheets-Sheet l 1N VEN TUR.

May 2l, 1 957 H. J. FLAIR BROACH CHECKING MACHINE 3 Sheets-Sheet 2 Filed March 9, 1956 May 2l, 1957 H. J. FLAIR 2,792,635

BROACH CHECKING MACHINE Filed March 9, 1956 3 Sheets-Sheet 3 INVENTOR. j

nited States Patent 2,792,636 BROACH CHECKING MACHINE Henry J. Flair, Chicago, Ill., assignor to Illinois Tool Works, Chicago, lll., a corporation of illinois Application March 9, 1956, Serial No. 570,473 6 Claims. (Cl. SiS-179.5)

This invention is concerned more specifically a machine broaches.

Analytical inspection machines capable of measuring lead, involute, and spacing of breaches to determine whether these measurements fall within prescribed standards of accuracy usually check yonly one of these elements or measurements. Ordinarily, three machines would be required to check the elements of lead, 'spacing, and involute of Ia broach. Many ingenious methods and apparatus have been used in the past for obtaining the requisite elements. Such methods and .apparatus generally have served satisfactorily for the analytical inspect-ion of gears, but they have had serious draw-backs when used for checking helical spline breaches.

The well known sine bar is often `with a testing machine, for inspecting helical used for producing` linear motion accurately relate-d t-o rotary motion. However, the sine bar fails when it is necessary, as in helical spline broach inspection, to have more than 360 rotation, or large linear movements.

Change gear machines have ybeen developed, utilizing ground helical master gears for providing .spindle rotation at a speed proportional to axial movement, when used in conjunction with a lead screw. However, `they are limited to approximately a six to one ratio and have the inherent angular velocity errors that exist even in the most accurate ground gears. Furthermore, when minimum proportions are used for the pinion, the mating part becomes too large for accurate grinding. Such a machine is sensitive to the character of tooth engagement as well as to the spacing, involute, lead, and center distance. While machines of this type function well on short leads where all ratios are favorable, they become quite inaccurate when used for leads of any magnitude.

Accordingly, it is an object of this invention to provide a new and improved machine for checking or inspecting helical spline broaches.

A further object of this invention is to provide a helif cal broach measuring machine capable :of measuring the magnitude of errors of the elements of lead, involute, and spacing.

`It is a further object of this invention to provide a checking head for an measuring machine for measuring Ithe magnitude of errors of lead, involute, and spacing.

'Other yand further objects and advantages of the present invention will be apparent from the following description when taken in connection with the vaccompanying drawings wherein:

AiFig. l is an elevational view of la machine constructed in accordance with the principles of the invention;

|Fig. 2 is an enlarged elevational view of the checking head;

IFig. 3 is van end view of `the checking head as taken from the left side of Fig. 2;

Fig. 4 is a detail view in horizontal section taken along the-line 4-4 of Fig. 3;

motions for checking the above noted otherwise more or less conventional Patented May 21, i957 ting -up or starting an operation, as is more or less in accordance with conventional practice. A tail stock 18 is provided .adjacent the opposite end of the bed, and steady rests 20 are adjustably spaced along the bed for supporting a helical vspline `broach 22. A lead screw 24 is provided in the bed below the dove Itail guide 16, and this lead screw is driven in synchronism with the head stock 17 from a common power source. Preferably, the head stock incorporates gearing of the type shown in Saarl Patent No. 2,696,125. This gearing provides extreme accuracy, and high reduction ratios. In a particular embodiment `of this invention, thegearing used in the head stock has a :1 ratio and has eight teeth in simultaneous contact.

A checking yor testing head 26 is mounted on `the b ed a lower slide 28 having a dove and adjusting screw means 34 is provided therefor in order to provide `a proper fit at all times.

The bed 14 and dove tail 16 thereof are provided with a longitudinal slot 36 A(Fig. 3) and a iixture 38 depends into this slot from the lower slide 28. This fixture is held lagainst the underside of `the lower slide by means of bolts 46 passing loosely through slots 42 in portions of the lower slide and threaded into the tixture 38.

The fixture 3d is provided with an upstanding central rib 44 (Figs. 3-5). The upper surface of the rib 44 is tapered, as is the confronting surface of the lower slide. Longitudinal adjustment of the fixture 38 relative to the lower slide thus effects raising and lowering of the lix-V ture for proper .cooperation with the feed screw as will be more apparent hereinafter. A plate 46 is held across la recess in the end of the lower slide by means such as -screws or bolts 48, and a screw 5l) passes through this plate along the bottom edge thereof, and is held against longitudinal movement relative to the plate. Thus, when the screw is threaded 'in or out of ya complementary tapped bore in the rib i4 it eiects the "aforementioned longitudinal movement of the fixture relative to the lower slide.

Wedges 52 are positioned on opposite sides of the rib 44, and have their tapered outer edges engaging complementary surfaces in an insert 54 in the lower slide. Longitudinal movement of these wedges is controlled by screws 56 passing through the lower edge of the plate 46 and threaded into the wedges. Longitudinal movement of these wedges effects transverse shifting of the iixture 38 for effecting proper lateral alignment of the xture with the lead screw. It will be understood that the bolts 40 are loosened whenever any adjustment of the fixture 38 is to be made.

The depending fixture 38 is provided with a cylindrical, longitudinally extending bore 58 (Fig. 5). A `pair ofelongated nut members 60 is received in this bor t.

arcanes f2 o* Thenut members are provided with internal threads receiving the lead screw 2li, and each nut member is provided at its o-uter end with a radially extending iange 62. The anges are provided with opposed arcuate slots 64, and screws or bolts 66 pass through these slots and thread into the depending fixture 38. Loosening oiA the screws 66 and rotation of one or both of the nut members a few degrees insures that one of the nut `.members will bear against one face of the threads of the Vlead screw 24, while the `other nut member will bear against the opposite face. As a result, backlash is eliminated.

A rod 63 (Fig. 2) `extends completely through the testing head lower slide and projects from the opposite ends thereof as is indicated at '7.0. The. central portionA of this'rod is provided with a restriction '72, .and aroller 74 on the end of an actuator for aswitch mechanism 76 is received in this restriction. (Dpposed .helicalsprings 7S normally centralize the rod 65d. However, .should the testing head tend to travel too far in'either. direction the appropriate projecting end 7d thereofwould engage a xed part to shift the rod longitudinally, and therebyA to actuate the switch mechanism 76, to'turn ofi the machine. The switch mechanism 76 is mounted and wired in conjunction with an electrical control unit 80 including push button means for starting, stopping, and reversing the machine. The switch mechanism and control mechanism both are of we ll known construction, and elaboration thereon accordingly is unnecessary.

The upper portion of the lower slide 28 is inclined at a shallow angle to the horizontal as is indicated. at 82, and is Vprovided with a longitudinal recess 84. The recess 8d is provided along its opposite longitudinal edges with bearing races 86 (Fig. 3) suitably held in place by screws or bolts 88. The bearing races 86 are provided with confronting V-shaped bail grooves 9d, and a plurality of'bearing balls 92' is rollingly received in these grooves and in confronting V-shaped grooves 94 of an upper slide 96. A stop $3 normally extends across the bottom of the upper slide to limit the downward movement thereof. This stop is, held in place by a bolt having a knurled knob 1d@ thereon, and upon loosening of this bolt the stop can be swung to the raised position shown in dashedlines in Fig. 5, thereby freeing the upper slide for downward movement.

An opstanding stop 102 is provided and is fixed to the lower portion of the upper slide by means such as one or more bolts 104 and suitable dowels 106 passing. through iianges on the stop 162 and extending into the upper slide. The stop102 is provided with a vertical edge 16S, anda scale 11th having indicia thereon is mounted' immediately' adjacent this vertical edge.

'A fixed involute head stop 112 (Figs. l, 2 and 5) is mounted so as to be adjnstably fixedin position on-top. ofthe bed 141, as by inteiiitting with the dove tail 16 and having suitable clamping means to lock it in place. The head stop is provided with a longitudinally extending" arm or finger 1111 having a ball 116 rotatably receivedy in the tip thereof. This ball is adapted to engage the vertical edge 103 of the stop 162. Thus, when the upper slide is released for up or down movement relative'to the lower slide, and the vertical edge 108 engages the ball 116 upon longitudinal feeding of the testing head by the screw 254, the lower slide will raise or lower the upperslide in the manner of a sine bar.

An upstanding bracket 118 (Figs. 2, 3, 5 and 6) is mounted on the upper slide 9d near the upper end thereof. The bracket 11d has a lower liange 120 inclined at the same angle to the horizontal as the top 82o`f the lower slide and the top of the upper slide. Bolts 122 pass. through this flange, and are threaded into the upper slide. A vertical web 124 of triangular coniiguration braces the bracket 11S.

The bracket 11S is provided o n its front face with a vertical dove tail 126 having a vertical groove or recess 128 therein extending back into the main portion ofthe bracket. Arollar 131i having lateral ears 132 v (Fig. 3) thereon is secured on top of the bracket by screws 134 passing through the ears. The collar is provided with a bearing 135, and a screw is mounted in the bearing and extends down into the vertical groove or recess 12d. The screw, hereinafter identified by the numeral 136, is provided with a circumferential flange 133 preventing vertical movement of the screw. A k-nurled handle 140 is provided at the Lipper end of the screw, and is provided with a crank handle 1,42.

A vertical slide 144 is mounted for up Vand down movement on. the bracket 11S, `and includes a dove tail guideway 146 receiving the dove tail slide 126. The guideway is provided with a nutdgi suitably :XQCi 1.0l the vertical slide, and this nut threadedly cooperates with the screw 135 for raising and lowering 'the vertical slide. A gib 159 is interposed between the dove tail slide 126 and groove 146. A screw or bolt (not shown) for adjustment of the gib is provided, as will be understood.

The vertical slide 144 is provided with a horizontal dove tail slide 152 havinga horizontal groove or recess 154 therein. A screw 156 extends through this recess and is journalcd at the opposite ends thereof in' the vertical slide. The right end ofthe screw (as viewed in Fig. 6) is provided with a knurled knob 158 having a crank handle 16) thereon. The knob is secured on the screw, and the screw is fixed against axial movement in much the same manner as was described with regard to the screw 136, namely by means such as a bolt on the upper end of the screw, or a cap screw threaded into a tapped bore in the upper end of the screw, and by a collar having laterally extending lugs thereon through which screws are threaded into the end of the vertical slide.

A horizontal slide 162 is provided with a horizontal dove tail slot or groove 164 receiving the horizontal dove tail 152 of the vertical slide. A nut 166 is suitably afiixed to the horizontal slide and extends into the horizontal recess 154 of the vertical slide, and threadedly receives the screw 156 whereby to shift the horizontal slide horizontally upon rotation of the screw 156 by the knob 158. A gib 168 is interposed between the horizontal dove tail 152 and an adjacent wall of the horizontal dove tail groove 164, and anadjusting screw 170 is provided therefor.

An arm 172 extends from one side of the horizontal slide, and then upwardly as at 174. The upwardly extending portion carries a pivot 176 of the needle bearingtype, and a clamp screw 178 adjustably secures the pivot 176 in place. A fixed pivot 134), also of the needle bearing type, is-mountedin the side wall of the horizontal slide in alignment with the pivot 176.

VA bell crank 182 is pivotally mounted between the pivots. 176 and 151i and includes a generally horizontally .extendingarm or socket portion 134. A testing linger 186 is heldin the socket portion by meansof a clamping screw 188. The testing finger may be of a type known inthe art for inspecting helicalv spline breaches. The bellcrank 152 further is provided with an angularly upstanding arm 188 having -a ball 19t) at the upper end thereof. i

Atesting unit 192 is mounted on the side of the horizontal slide 162 by bracket means 194. he testing unit comprises a conventional movement indicating gauge or meter 196 having a linear diiferential transformer 19S ofvknowndesign coupled thereto. A knurled knob 201i isprovided at one end of the testing unit for adjusting the idle position thereof, and the ball 19@ effects movement of the gauge and of the linear differential transformer. The gauge provides an instantaneous visual indication of errorsin the breach being tested, while the linear differential transformer is connected to a pen mechanism for making a permanent record on a moving paper tape (not shown).

The vertical slide 14d and bracket 118 are provided withcooperating scalemeans 202 ofn relatively coarse nature, and with rotary iine scale means-204-inconjuncareaeae tion with the knob M0. Similarly, cooperating scale means 206 (Fig. 3) is provided between the horizontal and vertical slides, and tine scale means 208 is provided in conjunction with the knob 158.

The knob M is used for setting the proper height of the vertical slide, and hence of the checking finger 136, above er below center relative te the breach 22 being tested. The scale means 202 and 204 indicate this height. The correct radius or checking depth is set by means of the knob d, which effects horizontal movement of the horizontal slide, the position being read on the scales 2de and 208.

For checking lead the testing head along the bed of the machine by the accordance with conventional practice, tion with rotation of the breach 22 of the synchronizing gears. Reaction of the breach on the testing linger 136 causes this finger to move up or down in accordance with errors. Such errors are indicated instantaneously on the gauge 196, and a permanent record thereof is made on the moving paper tape (not shown).

When it is desired to test for errors in invelute, the locking mechanism 93, 100 is released to allow more or less independent movement of the upper slide 96 relative te the lower slide er testing head base 28. The fixed involute head stop lll is locked in proper position, and the feed screw 24 advances the testing head until the ball 116 of the step i12 engages the vertical edge 108 of the stop or follower arm 102. This limits the upper slide against further horizontal movement, and as the lower slide continues to advance under the influence of the feed screw 2id, the upper slide moves vertically upwardly due to the enforced relative angular sliding movement en the lower slide. This movement is akin to that effected by the well known sine bar mechanism. The extent of vertical movement is measured by the scale U10.

Spacing errors are measured by indexing the breach one tooth at a time while moving the checking or testing head parallel to the breach axis by means of the lead screw 24.

It is te be understood that the specific example of the invention herein shown and described is set forth by way of illustration only. Various changes in structure will no doubt occur to those skilled in the art, and such changes are to be understood as being within the contemplation of this invention insofar as they fall within the spirit and scope of the appended claims.

The invention is claimed as follows:

1. ln a machine for testing helical spline breaches having breach supporting and rotating means, a bed extending parallel to a breach supported by said breach supporting means, and feeding means operating in timed relation with said breach rotating means, a testing head comprising a base, said base having slide means thereon inclined at an acute angle te said bed, cooperating slide means movable relative to said base and intertting with the first mentioned slide means, testing means engageable with a breach, means carrying said testing means from the second mentioned slide means for effecting movement of said testing means toward and away from said bed 2d simply is fed lead screw 24 in and in timed relaunder test by virtue `by to produce movement and means for moving said testing means toward and away from the breach and substantially parallel te said bed, and means mounted on said bed and engageable with the second mentioned slide means for effecting sliding thereof upon movement of the base along the slide whereof the testing means perpendicular to said bed.

2. A testing head as set forth in claim 1 and further including means for securing the two slide means together for movement as a unit.

3. ln a machine for testing helical spline breaches having breach supporting and rotating means, a bed extending parallel to a breach supported by said breach supporting means, and feeding means operating in timed relation with said breach rotating means, a testing head comprising a base, means mounting said base on said bed for movement therealong, means operatively interconnecting said base and said feeding means for feeding said base along said bed in timed relation to rotation of a breach rotated by said breach rotating means, said base having inclined slide means thereon forming an acute angle with said bed, second slide means intertting with said first mentioned slide means and slidable therein at said acute angle relative to said bed, testing means engageable with a breach, means supporting said testing means from said second mentioned slide means, and a stop mounted en said bed and engageable with said second mentioned slide means for effecting movement thereof relative to said base to produce movement of said testing means perendicular te said bed in response to movement of said base along said bed.

4. A testing head as set forth in claim 3 wherein the testing means supporting means comprises a bracket mounted on the second mentioned slide means, means mounted on said bracket for movement thereon substantially perpendicular to said bed, and means mounted on the last mentioned means and movable relative thereto parallel to the bed and substantially perpendicular to the breach.

5. A machine for testing helical spline breaches as set forth in claim 1, wherein said testing means consists of a bell crank testing element having one end thereof engageable with a breach, pivot means pivetally supporting the bell crank testing element substantially at the apex thereof, means engaged by the other end of said bell crank testing element for interpreting movement thereof in accordance with errors in the breach, and means supporting said pivot means from said second slide means.

6. A machine for testing helical spline breaches as set forth in claim l, wherein said breach rotating means consists of a worm and worm gear nnit, said worm gear being of a face type worm gear cooperable with a worm made from a conical blank of moderate taper, the ratio being in excess of 9 to 1.

References Cited in the le of this patent UNITED STATES PATENTS 2,046,506 Drader July 7, 1936 2,336,845 Christensen Dec. 14, 1943 2,563,000 Bean Aug. 7, 1951 

